This invention relates to methods for composite rendering of 3-dimensional (“3-D”) graphical objects.
In the field of graphic arts, much effort is spent creating realistic looking images of objects in a virtual world. In order to view the objects in the virtual world from an arbitrary vantage point, the objects must be stored as 3-D objects. These 3-D objects can then be rendered to 2-D images or scenes appropriate for display on an output device such as a printer or monitor using a variety of 3-D rendering algorithms. Many 3-D rendering algorithms include image processing effects that add realism to the rendered 2-D scenes including anti-aliasing, motion-blur, and depth-of-field effects. Notably, however, all of the algorithms that allow a 3-D scene to be rendered with combined anti-aliasing, motion-blur, and depth-of-field effects, require the individual components of the scene to be rendered together in the same rendering step.
A current goal of 3-D rendering is to develop a 3-D image compositing technique that would allow separately rendered 3-D objects to be seamlessly integrated into realistic looking composite scenes. The advantages of developing such a 3-D image compositing technique are obvious. The technique would allow 3-D images and objects from different sources made at different times to be seamlessly integrated into arbitrary composite scenes. It would allow objects easily to be added to and removed from a scene without having to re-render the entire scene. It would also allow for objects to be separately created, rendered, and realistically used and re-used in a multitude of different scenes.
While there has been some work in the field of 3-D image compositing, and while some commercial 3-D compositing systems have recently come into use, no system has been able successfully to incorporate all of the image processing effects that would allow realistic looking 3-D composited scenes to be created. In particular, the effects of anti-aliasing, motion-blur, and depth of field have not been successfully incorporated into any 3-D image compositing system such that a composited image produced by the system is of the same quality as can be achieved by rendering all of the separately composited image elements together using a standard 3-D rendering system. Recently, the anti-aliasing problem has been solved; however, there is no current solution for motion blur and depth-of-field effects of separately composited objects, specifically with respect to intersecting objects.